Coil bobbin, coil component and switching power source apparatus

ABSTRACT

To improve insulating properties of a coil winding having three turns. In a coil bobbin, insulation between mutually adjacent winding members of a first coil winding are achieved by a projecting section. Furthermore, the first coil winding and the second coil winding are insulated from each other by the flange section. Moreover, the projecting sections and the projecting sections are respectively provided in positions at either end when the first coil winding and the second coil winding are viewed in a direction perpendicular to the direction of the axis line. Consequently, even with coil windings having three turns, insulation between the windings is achieved by means of this coil bobbin, and furthermore, insulation is also achieved in the region outside the coil windings as viewed in a direction perpendicular to the axis line direction, thereby making it possible to improve the insulating properties without increasing the number of parts.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a coil bobbin, a coil component and aswitching power source apparatus.

2. Related Background Art

Coils formed with a plurality of coil windings having two turns, forinstance, are being used increasingly in switching power source deviceswhich are incorporated into a charger for a vehicle-mounted battery. Inresponse to this, Japanese Patent Application Publication No.2010-45188, for example, discloses a coil bobbin provided with aprojecting section that projects outwards from an externalcircumferential surface of a tubular main body section, so as to avoidcontact and shorting between coil windings having two turns.

In recent years, the use of coils having three or more turns hasincreased with the object of improving the output current. In this case,in order to improve insulating properties between mutually adjacentwindings, a method of providing insulating members respectively betweenthe windings is used, for instance. However, if the number of partsincreases, then the number of steps involved in coil assembly alsoincreases.

SUMMARY OF THE INVENTION

The present invention was devised in view of the foregoing, an objectthereof being to provide a coil bobbin whereby insulating propertiesbetween coil windings having three turns can be improved, withoutincreasing the number of parts, and to provide a coil component and aswitching power source device using this coil bobbin.

In order to achieve the aforementioned object, the coil bobbin relatingto one aspect of the present invention is an insulating coil bobbinhaving a tubular section about which two conductive coil windings arewound, this coil bobbin further having: a flat-shaped flange sectionwhich projects outwards from substantially a central portion of thetubular section in a plane which is perpendicular to an axis line of thetubular section; a first projecting section which projects towardoutside from the tubular section with respect to the axis line at aposition separated from the flange section, the first projecting sectionprojecting further toward outside than a first coil winding, which hastwo or more turns, of the two coil windings, when the first coil windingis wound on a first end side, this first end side being one end side ofthe tubular section as divided by the flange section and being the sidewhere the first coil winding is wound; a second projecting section,which is provided so as to be sandwiched between adjacent windings whenthe first coil winding is wound on the first end side and which projectstoward outside from the tubular section with respect to the axis line,in a direction different from the first projecting section when viewedin the axis line direction; and a third projecting section whichprojects toward outside from the tubular section with respect to theaxis line at a position separated from the flange section, the thirdprojecting section projecting further toward outside than a second coilwinding, which is different from the first coil winding, of the two coilwindings, and which has one or more turns, when the second coil windingis wound on a second end side, this second end side being a differentend side from the first end side of the tubular section and being a sidewhere the second coil winding is wound.

According to the coil bobbin described above, mutually adjacent windingwires of the first coil winding which has two or more turns areinsulated by the second projecting section. Furthermore, the first coilwinding and the second coil winding, which has one or more turns, areinsulated from each other by the flange section. Moreover, the firstprojecting section and the third projecting section are provided inpositions at either end of the first coil winding and the second coilwinding when viewed in a direction perpendicular to the axis linedirection. In this way, according to the coil bobbin described above,even with coil windings having three turns, insulation between thewinding wires is achieved by means of this coil bobbin, and furthermore,insulation is also achieved in the region outside the coil windings asviewed in a direction perpendicular to the axis line direction, therebymaking it possible to improve the insulating properties withoutincreasing the number of parts.

Here, it is possible to adopt a mode in which the flange section has anouter diameter larger than an outer diameter of the coil windings, andcomprises a side wall section extending in the axis line direction froman outer circumferential edge thereof.

As described above, by making the flange section larger than the outerdiameter of the coil windings and providing a side wall section whichextends in the direction of the axis line from the outer circumferentialedge, then it is possible to achieve insulating properties between thecoil windings and members such as the magnetic core members, and thelike, provided to the outside thereof, as well as achieving stabilitywhen installing the coil windings on the coil bobbin.

Furthermore, it is also possible to adopt a mode in which a height of aside wall section in the axis line direction is greater than a thicknessof a coil winding provided in the direction in which the side wallsection extends, and the side wall section further has a hook sectionwhich extends in the axis line direction from an end of the side wallsection that is different from the end on the side of the flangesection.

By providing a hook section extending in the axis line direction fromthe side wall section as described above, the hook section presses inthe coil winding which is provided in the direction of extension of theside wall section, when viewed in a direction perpendicular to the axisline direction, and therefore vibration of the coil winding in the axisline direction with respect to the coil bobbin can be suppressed andinsulating properties can be improved.

Furthermore, it is also possible to adopt a mode comprising rotationrestricting means for restricting rotation in one direction of the coilwinding, by abutting against the coil winding when the coil winding isinserted into the tubular section and rotated.

By providing rotation restricting means for restricting rotation of thecoil winding in one direction, it is possible to prevent the coilwinding from contacting other components, for example, due to rotatingabout the circumference of the tubular section of the coil bobbin, andtherefore the insulating properties of the coil winding can be improved.

Here, it is also possible to adopt a mode which further comprisesreversal restricting means for restricting rotation of the coil windingin a reverse direction at a position where rotation of the coil windingin the one direction has been restricted by the rotation restrictingmeans.

By providing reversal restricting means which restricts rotation in theopposite direction to the rotation in the one direction, as describedabove, rotation of the coil winding in the reverse direction is alsosuppressed and the coil winding can be fixed more securely at aprescribed position.

The coil component relating to one aspect of the present inventioncomprises: the coil bobbin described above; a first coil winding whichis wound in two or more turns about the axis line; a second coil windingwhich is wound in one or more turns about the axis line; a connectingmember which connects one end section of the first coil winding with oneend section of the second coil winding; and a pair of magnetic coremembers which sandwich the coil windings in the axis line direction. Inthis case, it is possible to obtain a coil component having raisedinsulating properties, without raising the number of parts, using a coilwinding having three or more turns in which a first coil winding and asecond coil winding are connected by a connecting member.

Moreover, the switching power source apparatus relating to the presentinvention comprises the coil component described above. In this case, itis possible to obtain a switching apparatus having raised insulatingproperties using a coil winding of three turns, without increasing thenumber of parts.

According to the present invention, a coil bobbin which can improve theinsulating properties of coil windings having three turns, a coilcomponent using this coil bobbin, and a switching power sourceapparatus, are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective diagram showing a coil bobbin relatingto an embodiment of the present invention, and a first coil windingwhich is installed on the coil bobbin;

FIG. 2 is a perspective diagram from a bottom surface side of the coilbobbin in FIG. 1;

(a) of FIG. 3 is a plan diagram of a coil bobbin, and (b) of FIG. 3 is afront view diagram of a coil bobbin (a diagram viewed from the Xdirection in FIG. 1);

(a) of FIG. 4 is a bottom surface diagram of a coil bobbin and (b) ofFIG. 4 is a rear surface diagram of a coil bobbin;

(a) of FIG. 5 is a plan diagram of a first coil winding in FIG. 1 and(b) of FIG. 5 is a bottom surface diagram of a first coil winding;

FIG. 6 is a side view diagram of a first coil winding;

FIG. 7 is a diagram for describing a method of installing a first coilwinding on a coil bobbin;

FIG. 8 is a diagram for describing the composition of a part obtained byinstalling a first coil winding on a coil bobbin, and a second coilwinding;

(a) of FIG. 9 is a plan diagram of a second coil winding and (b) of FIG.9 is a bottom surface diagram of a second coil winding;

FIG. 10 is a diagram for describing a method of installing a second coilwinding on a part constituted by a coil bobbin and a first coil winding;

FIG. 11 is a diagram for describing a method of connecting a first coilwinding and a second coil winding;

FIG. 12 is a perspective diagram of a bottom surface side of a coilconsisting of a coil bobbin, a first coil winding and a second coilwinding;

FIG. 13 is a front view diagram of a coil (as viewed in the X directionin FIG. 1);

FIG. 14 is an exploded perspective diagram for illustrating thecomposition of a coil component;

FIG. 15 is a circuit diagram of a switching power source apparatus;

FIG. 16 is a perspective diagram of a switching power source apparatus;

FIG. 17 is an exploded perspective diagram of a case where a heatradiating member is installed on a coil component; and

FIG. 18 is a perspective diagram of a coil component in which a heatradiating member is installed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Below, a mode of implementing the present invention is described indetail with reference to the accompanying drawings. In the descriptionof the drawings, the same elements are labeled with the same referencenumerals, and repeated description is omitted.

FIG. 1 is an exploded perspective diagram showing a coil bobbin relatingto the present embodiment, and a first coil winding which is installedon the coil bobbin. FIG. 2 is a perspective diagram from a bottomsurface side (rear surface side) of the coil bobbin in FIG. 1.Furthermore, (a) of FIG. 3 is a plan diagram of a coil bobbin, and (b)of FIG. 3 is a front view diagram of a coil bobbin (a diagram viewedfrom the X direction in FIG. 1). Moreover, (a) of FIG. 4 is a bottomsurface diagram of a coil bobbin and (b) of FIG. 4 is a rear surfacediagram of a coil bobbin. The detailed composition of the first coilwinding shown in FIG. 1 is described below.

A coil component constituted by the coil bobbin 1 shown in FIG. 1 andthe first coil winding 2 is used in an inductance element, a switchingpower source apparatus, a noise filter, an inverter, or the like. Thecoil component includes a second coil winding 3, a connection member 4,and a pair of magnetic core members 5A, 5B, in addition to the coilbobbin 1 and the first coil winding 2 described above. The compositionof these elements is described below.

The respective parts which constitute the coil component 1 describedabove will now be explained, together with the method of assembly of thecoil component 1.

(Coil Bobbin)

Firstly, the composition of the coil bobbin 1 included in the coilcomponent relating to the present embodiment will be described withreference to FIG. 1 to FIG. 4. The coil bobbin 1 is made of aninsulating material, such as resin, and is constituted by a tubularsection 10, a flange section 11 which is provided in substantially thecentral portion of the tubular section 10 and which projects outwardswith respect to the axis line A, and projecting sections 12A to 12C, 13,14A and 14B. Of these parts, the projecting sections (first projectingsections) 12A to 12C and the projecting section (second projectingsection) 13 are provided on an upper side of the flange section 11 asdepicted in FIG. 1, and the projecting sections (third projectingsections) 14A, 14B are provided on a lower side (bottom surface side) ofthe flange section 11 as depicted in FIG. 1, Moreover, the projectingsections 12A to 12C are provided on the upper side end portion of thetubular section 10 as depicted, and the projecting section 13 isprovided in substantially a central portion of the tubular section 10,at a position between the upper side end portion of the tubular section10 and the flange section 11. The position where the projecting section13 is provided is determined by the shape of the first coil winding (thethickness of the winding, etc.) which is described hereinafter. As shownin (a) of FIG. 3, the projecting sections 12A to 12C and the projectingsection 13 are provided at mutually different positions when viewed fromabove along the axis line A. Furthermore, the projecting sections 14A,14B are provided respectively on a lower side end portion of the tubularsection 10.

The flange section 11 is a member which is flat and projects outwardsfrom the tubular section 10, and functions as spacer that insulates thefirst coil winding 2 and the second coil winding 3. Furthermore, theflange section 11 is provided with a region having a larger outerdiameter than the first coil winding 2 and the second coil winding 3,when viewed along the direction of the axis line A. The flange section11 has a side wall section 15 which extends downwards along thedirection of the axis line A on the outer side of the flange section.This side wall section has a substantially circular arc shape whichcorresponds to the shape of the second coil winding 3, as describedhereinafter, and has a function for maintaining insulation between thesecond coil winding 3 and a core member 5A which is describedhereinafter. Moreover, as shown in FIG. 2, a hook section 16 whichprojects in the direction of the axis line A is provided on a lower endportion of the side wall section 15. As shown in (b) of FIG. 3, thishook section 16 is provided at the same height as the lower projectingsections 14A and 14B.

Moreover, as shown in FIG. 1 and FIG. 3, a cover section (spacersection) 17B extending in a plane perpendicular to the direction of theaxis line A is provided on the upper side of the flange section 11 inthe height direction. A wall section 17A which connects between thecover section 17B and the flange section 11 is provided along thedirection of the axis line A. Moreover, a hook section 17C whichprojects downwards is provided on the outer side end portion of thecover section 17B with respect to the axis line A. The function of theseelements is described below. As shown in (b) of FIG. 3, a substantiallysquare U-shaped region is formed by the wall section 17A, the coversection 17B and the hook section 17C, and this has a function ofsecuring the first coil winding 2 which is described below (rotationrestricting means, reversal restricting means).

Furthermore, a cover section (spacer section) 18A which projectsoutwards is provided in the flange section 11 in a separate region fromthe side wall section 15, and a hook section 18B which projectsdownwards from the outside end portion of the cover section 18A is alsoprovided. This hook section 18B has a function of securing the secondcoil winding 3, which is described hereinafter.

Leg sections 19A to 19D for engaging the coil bobbin 1 with the coremembers 5A, 5B are provided in an integrated fashion in the end portionof the side wall section 15. The leg sections 19A to 19D have a shapethat corresponds to the shape of the core members 5A, 5B.

When a coil bobbin 1 having the composition described above is viewed inthe direction of the central axis line A of the tubular section 10 (theupper side in FIG. 1), then as shown in (a) of FIG. 3, the tubularsection 10, the projecting sections 12A to 12C, 13, 14A, 14B and theflange section 11 and the cover section 17B do not have any mutuallyoverlapping portions. Therefore, the coil bobbin 1 can be manufacturedreadily by injection molding of an insulating resin, using a die.

(First Coil Winding)

Next, a first coil winding 2 shown in FIG. 1 will be described withreference to FIGS. 1, 5 and 6. (a) of FIG. 5 is a plan view diagram ofthe first coil winding in FIG. 1, (b) of FIG. 5 is a bottom surfacediagram of the first coil winding and FIG. 6 is a side view diagram ofthe first coil winding.

As shown in FIG. 1 and FIG. 5, the first coil winding 2 substantiallyhas a circular ring shape which is formed by joining together twowinding members 21, 22, each shaped as a ring with an end, which aresituated in parallel at a distance apart and are joined together so asto connect in a prescribed winding direction. A “substantially circularring shape” means that, of the coil winding, the outer circumference ofthe region forming the winding (in other words, the region apart fromthe terminal sections or the connecting section, and the like) has anapproximately circular shape, or an approximately elliptical shape, whenviewed in the direction of the axis line A. The winding members 21, 22,which are shaped as a ring with an end, take the form of the letter Cand have a circular opening 201, 202 in the center thereof. The wiringmember 21 and the wiring member 22 are mutually overlapped in such amanner that these openings 201 and 202 are connected. A slit 23 and aslit 24 are respectively provided in the winding member 21 and thewinding member 22, but these slits are mutually overlapping at staggeredpositions when viewed in the axis line direction (in other words, so asnot be connected). The slit 24 is a slit into which the projectingsection 13 passes when the first coil winding 2 is installed on the coilbobbin 1.

Moreover, a first terminal section 25 which projects outwards from theaxis line A of the opening 201 is provided in an integrated fashion onone end portion of the winding member 21. The other end portion of thewinding member 21 is connected to one end portion of the winding member22 via a U-shaped connecting section 26. A second terminal section 27which projects outwards from the axis line A of the opening 202 isprovided in an integrated fashion on the other end portion of thewinding member 22. In the first coil winding 2 which has the compositiondescribed above, the first terminal section 25 is a starting end of thefirst coil winding 2, and the second terminal section 27 is a final endof the first coil winding 2. When electric power is input to the firstterminal section 25, the power flows sequentially through the windingmember 21, the connecting section 26 and the winding member 22, and isoutput from the second terminal section 27.

Moreover, a heat radiating section (heat radiating terminal) 28 whichprojects outwards from the axis line A is provided in the winding member22. This heat radiating section 28 has a function of fixing the firstcoil winding 2 and the coil bobbin 1 so as not to become detached due tovibration, and the details thereof are described hereinafter.

A plurality of notch sections 211, 212, 213 (in the present embodiment,three notch sections) which are cut in an outward direction are formedin the internal circumference of the winding member 21. The notchsections 211 to 213 are arranged in a mutually separate fashion alongthe circumferential direction of the opening 201.

Furthermore, a plurality of notch sections 221, 222, 223 (in the presentembodiment, three notch sections) which are cut in an outward directionare formed in the internal circumference of the winding member 22. Thenotch sections 221 to 223 are arranged in a mutually separate fashionalong the circumferential direction of the opening 202. The notchsections 211 to 213 of the winding member 21 and the notch sections 221to 223 of the winding member 22 are provided at overlapping positionswhen viewed in the direction of the axis line A, as shown in FIG. 1 andFIG. 5. The notch sections 211 to 213 and the notch sections 221 to 223are provided at positions corresponding to the projecting sections 12Ato 12C which are provided on the tubular section 10 of the coil bobbin1.

The first coil winding 2 which has the composition described above canbe formed by punching out from a single sheet having high electricconductivity. More specifically, a first terminal section 25, windingmembers 21, 22 which connect to the first terminal section 25, a secondterminal section 27 which connects to the winding member 22, a heatradiating section 28 which extends from the winding member 22, and anI-shaped connecting section 26 which connects the winding members 21,22, can be processed by punching out from a sheet of copper or aluminum,or the like. The winding members 21 and 22 are mutually superimposed ata prescribed gap apart by bending the connecting section 26 in a Ushape. By this means, a first coil winding 2 consisting of conductiveplate is completed. The first coil winding 2 is not limited to a bentcoil of this kind; for example, it may also be formed by screw fasteningor welding together a coil member and a connecting section. Furthermore,these elements may also be fixed by rivets.

(Installing the First Coil Winding on the Coil Bobbin)

Next, the installation of the first coil winding 2 on the coil bobbin 1will be described with reference to FIG. 1 and FIG. 7. FIG. 7 is adiagram which describes a method of installing a first coil winding on acoil bobbin, and corresponds to a plan diagram of the coil bobbin andthe first coil winding.

As shown in FIG. 1, the rear surface of the winding 22 (the bottomsurface side in FIG. 1), of the first coil winding 2, is set tocorrespond to the end side (first end side) of the coil bobbin 1, wherethe projecting sections 12A to 12C and 13 are provided. The position ofthe projecting section 12A of the coil bobbin 1 is matched to the notchsections 211, 221 of the winding members 21, 22. By matching thesepositions, the projecting section 12B is matched to the position of thenotch sections 212, 222, and the projecting section 12C is matched tothe position of the notch sections 213, 223. Furthermore, the positionsof the projecting section 13 of the coil bobbin 1 and the slit 24 of thewinding member 22 are also matched. After matching the positions, thefirst coil winding 2 and the coil bobbin 1 are moved relatively, and thetubular section 10 of the coil bobbin 1 is inserted in the direction ofthe central axis line A of the tubular section 10, into the openings201, 202 of the winding members 21, 22. As the tubular section 10 isinserted, the projecting sections 12A to 12C pass into the notchsections 211 to 213 and 221 to 223 and the projecting section 13 passesinto the slit 24.

When the tubular section 10 is inserted, the flange section 11 of thecoil bobbin 1 abuts against the rear surface of the winding member 22.By this means, it becomes impossible to insert the coil bobbin 1further, and hence the coil bobbin 1 assumes the state shown in (a) ofFIG. 7. In this state, the projecting sections 12A to 12C of the coilbobbin 1 project slightly from the notch sections 211 to 213 of thewinding member 21. Furthermore, the projecting section 13 is positionedbetween the winding member 21 and the winding member 22.

Next, the coil bobbin 1 is rotated relatively with respect to the firstcoil winding 2. (b) of FIG. 7 is a diagram showing a state where thecoil bobbin 1 is rotated through approximately 180 degrees with respectto the coil winding 2.

More specifically, the coil bobbin 1 is rotated leftwards when viewedfrom above in FIG. 1. When this rotation starts, the projecting section12A of the coil bobbin 1 leaves the notch section 211 of the windingmember 21, and the projecting sections 12B, 12C also leave the notchsections 212, 213 of the winding member 21. When the coil bobbin 1 isrotated through 180 degrees, the heat radiating section 28 of thewinding member 22 enters in below the cover section 17B of the coilbobbin 1. In this case, although there is a hook section 17C whichprojects from the cover section 17B, the cover section 17B which is madeof an insulating resin flexes, and hence the heat radiating section 28enters below the cover section 17B. The wall section 17A of the coilbobbin 1 abuts against the heat radiating section 28 of the windingmember 22. Due to the heat radiating section 28 abutting against thewall section 17A, further rotation in this direction is restricted. Inother words, the wall section 17A functions as rotation restrictingmeans. Furthermore, when the heat radiating section 28 abuts against thewall section 17A, the whole of the heat radiating section 28 enters inbelow the cover section 17B, and therefore the flexion of the coversection 17B returns to its original state, and the hook section 17Ccovers a portion of the outside of the heat radiating section 28 in thedirection of the axis line A. As a result of this, rotation of the firstcoil winding 2 in the reverse direction with respect to the coil bobbin1 is restricted by the hook section 17C. More specifically, the hooksection 17C functions as reversal restricting means. In this case, asshown in (b) of FIG. 7, the winding members 21, 22 of the first coilwinding 2 are formed with a smaller external diameter than the flangesection 11.

In this case, insulation between the winding member 21 and the windingmember 22 is achieved by the projecting section 13 of the coil bobbin 1.Moreover, by rotating the coil bobbin 1 with respect to the first coilwinding 2, as shown in (b) of FIG. 7, the projecting sections 12A to 12Cof the coil bobbin 1 and the notch sections 211 to 213 of the windingmember 21 assume mutually different positions when viewed in thedirection of the axis line A, and therefore movement of the first coilwinding 2 in the direction of the axis line A is also restricted by theprojecting sections 12A to 12C.

(Second Coil Winding)

Next, the second coil winding will be described with reference to FIG. 8and FIG. 9. FIG. 8 is a diagram for describing the composition of acomponent in which a first coil winding is installed on a coil bobbin,and the composition of a second coil winding. (a) of FIG. 9 is a plandiagram of a second coil winding and (b) of FIG. 9 is a bottom surfacediagram of a second coil winding.

As shown in FIG. 8 and FIG. 9, the second coil winding 3 has asubstantially circular ring shape and is constituted by a winding member31 shaped as a ring with an end. This winding member 31 is in the formof the letter C and has a circular opening 301 in the center thereof.Moreover, the winding member 31 is a one-turn winding, and a thirdterminal section 32 which projects outwards from the axis line A of theopening 301 is provided in an integrated fashion on one end portion ofthe winding member 31. A fourth terminal section 33 which projectsoutwards from the axis line A of the opening 301 is provided in anintegrated fashion on the other end portion of the winding member 31. Aslit 34 is provided between the third terminal section 32 and the fourthterminal section 33.

Moreover, a heat radiating section (heat radiating terminal) 35 whichprojects outwards from the axis line A is provided on the winding member31. This heat radiating section 35 is a region for ensuring the width ofthe winding member 31 (cross-sectional area), as well as functioning asa member for raising the heat radiating properties from the second coilwinding 3.

A plurality of notch sections 311, 312 (in the present embodiment, twonotch sections) which are cut in an outward direction are formed in theinternal circumference of the winding member 31. The notch sections 311and 312 are arranged in a mutually separate fashion along thecircumferential direction of the opening 301.

The second coil winding 3 which has the composition described above canbe formed by punching out from a single sheet having high electricconductivity.

(Installing the Second Coil Winding on the Coil Bobbin)

Next, the installation of the second coil winding on a componentconstituted by the coil bobbin and the first coil winding will bedescribed with reference to FIGS. 8, 10, 11 and 12. FIG. 10 is a diagramfor describing a method of installing a second coil winding on acomponent constituted by a coil bobbin and a first coil winding.Furthermore, FIG. 11 is a diagram for describing a method of connectinga first coil winding and a second coil winding, and FIG. 12 is aperspective diagram of a bottom surface side of a coil constituted by acoil bobbin, a first coil winding and a second coil winding.

As shown in FIG. 8, the rear surface of the second coil winding 3 (thebottom surface side in FIG. 8) is made to correspond to the end sectionside (second end section side) of the coil bobbin 1 where the projectingsections 14A, 14B are provided. The position of the projecting section14A of the coil bobbin 1 is matched to the notch section 311 of thewinding member 31. By matching these positions, the projecting section14B is matched in position to the notch section 312. After positionalalignment, the second coil winding 3 and the coil bobbin 1 are movedrelatively, and the tubular section 10 of the coil bobbin 1 is insertedinto the opening 301 of the winding member 31, in the direction of thecentral axis line A of the tubular section 10. With this insertion ofthe tubular section 10, the projecting sections 14A, 14B pass into thenotch sections 311, 312. By this means, the surface 11 b of the flangesection 11 of the coil bobbin 1 abuts against the rear surface of thewinding member 31. Consequently, it becomes impossible to insert thecoil bobbin 1 further, and hence the coil bobbin 1 assumes the stateshown in (a) of FIG. 10. In this case, the side wall section 15 of thecoil bobbin 1 assumes a position covering the outer circumferential edgeof the second coil winding 3 (see (a) of FIG. 10).

Next, the second coil winding 3 is rotated relatively with respect tothe component 1A constituted by the coil bobbin 1 and the first coilwinding 2. (b) of FIG. 10 is a diagram showing a state where the secondcoil winding 3 has been rotated through approximately 10 degrees withrespect to the component 1A.

More specifically, the second coil winding 3 is rotated rightwards asviewed from the upper side in FIG. 8. Due to this rotation, theprojecting section 14A of the coil bobbin 1 leaves the notch section 311of the winding member 31, and the projecting section 14B also leaves thenotch section 312 of the winding member 31. When the second coil windingis rotated through 10 degrees, the heat radiating section 35 of thewinding member 31 moves until reaching a position superimposed over thecover section 18A of the coil bobbin 1. In this case, although there isa hook section 18B which projects from the cover section 18A, the coversection 18A which is made of insulating resin flexes, and therefore theheat radiating section 28 can ride up over the hook section 18B andbecome superimposed over the cover section 18A. Furthermore, in thiscase, the region of the winding member 31 which extends to the fourthterminal section 33 abuts against the side wall section 15, andmoreover, the winding member 31 also enters in below the hook section 16provided in the side wall section 15. Accordingly, further rotation inthis direction is suppressed. In other words, the side wall section 15functions as rotation restricting means. Furthermore, when the windingmember 31 abuts against the side wall section 15, the heat radiatingsection 35 moves until completely riding over the hook section 18B, andtherefore the flexion of the cover section 18A returns to the originalshape and the hook section 18B covers the outside portion of the heatradiating section 35 when viewed in the direction of the axis line A. Asa result of this, rotation of the second coil winding 3 in the reversedirection with respect to the coil bobbin 1 is restricted by the hooksection 18B. More specifically, the hook section 18B functions asreversal restricting means. In this case, as shown in (b) of FIG. 10,the second coil winding 3 is accommodated to the inner side of the sidewall section 15.

Furthermore, by rotating the second coil winding 3 with respect to thecoil bobbin 1, as shown in (b) of FIG. 10, the projecting sections 14Aand 14B of the coil bobbin 1 and the notch sections 311 and 312 of thewinding member 31 assume mutually different positions when viewed in thedirection of the axis line A, in addition to which the winding member 31enters in below the hook section 16, and therefore movement of thesecond coil winding 3 in the direction of the axis line A is alsorestricted by the projecting sections 14A and 14B.

By rotating the second coil winding 3 with respect to the coil bobbin 1,the second terminal section 27 of the first coil winding 2 and the thirdterminal section 32 of the second coil winding 3 assume mutuallyoverlapping positions when viewed in the direction of the axis line A.Therefore, by electrically connecting the second terminal section 27 ofthe first coil winding 2 and the third terminal section 32 of the secondcoil winding 3, by a screw (connecting member) 4, as shown in FIG. 11,the first coil winding 2 and the second coil winding 3 function as acoil winding having a total of three turns. More specifically, whenpower is input to the first terminal section 25 of the first coilwinding 2, the power arrives at the second terminal section 27 bypassing along the winding member 21, the connecting section 24 and thewinding member 22, and then passes along the winding member 31 from thethird terminal section 32 of the second coil winding 3 which iselectrically connected to the second terminal section 27, arrives at thefourth terminal section 33, and is then output from the fourth terminalsection 33.

Furthermore, by fixing the second terminal section 27 of the first coilwinding 2 and the third terminal section 32 of the second coil winding 3by the screw 4, movement of the first coil winding 2 and the second coilwinding 3 on the outer side of the tubular section 10 is restricted.Rather than using screw fixing, the coil windings may be connected bywelding. Furthermore, the coil windings may also be fixed by rivets.

By the foregoing, a coil 1B consisting of a coil bobbin 1, a first coilwinding 2, a second coil winding 3 and a screw 4 serving as a connectingmember is formed.

FIG. 13 shows a front view diagram of the coil 1B (a view in the Xdirection in FIG. 1). As shown in FIG. 13, in the coil 1B, theprojecting section 13 of the coil bobbin 1 is provided between thewinding member 21 and the winding member 22 of the first coil winding 2,thereby achieving insulation. Moreover, a flange section 11 is providedbetween the winding member 22 and the second coil winding 3 (windingmember 31), thereby achieving insulation. Furthermore, projectingsections 12A to 12C are provided above the winding member 21 (only theprojecting section 12A is shown in FIG. 13), thereby suppressing upwardmovement of the winding member 21. Furthermore, projecting sections 14Aand 14B (only the projecting section 14A is shown in FIG. 13) and thehook section 16 are provided below the winding member 31, therebysuppressing downward movement of the winding member 31.

(Coil Component)

Next, a coil component 1C will be described with reference to FIG. 14.FIG. 14 is an exploded perspective diagram for illustrating thecomposition of a coil component. In this coil component 1C, the coil 1Bdescribed above is also provided with a pair of magnetic core members 5Aand 5B. The coil component 1C functions, for example, as a choke coil ofthe switching power source apparatus described below.

As shown in FIG. 14, the magnetic core members 5A, 5B are arranged so asto sandwich the coil 1B along the axis line A and pass through theopening of the coil bobbin 1 constituting the coil 1B.

The magnetic core members 5A, 5B each respectively constitute aso-called E-shaped core which is obtained by compacting a ferritepowder. More specifically, the magnetic core member 5A consists of aflat plate-shaped base section 50 having a lengthwise direction, acircular rod-shaped main leg 51 which is provided in a projectingfashion in the center of one main surface of the base section 50, andtwo outer legs 52, 53 provided at end portions of the base section 50 oneither side of the main leg 51. Furthermore, the magnetic core member 5Bis also constituted by a base section 54, a main leg 55 and two outerlegs 56, 57.

The main legs 51, 55 of the magnetic core members 5A, 5B are insertedinto the opening of the coil 1B, in other words, the openings 201 and202 of the tubular section 10 of the coil bobbin 1. In this case, thefirst coil winding 2 and the second coil winding 3 are provided on theoutside of the tubular section 10, and therefore the main legs 51, 55 donot contact these windings.

Furthermore, the outer legs 52, 53 of the magnetic core member 5A andthe outer legs 56, 57 of the magnetic core member 5B are arranged aboutthe outer circumference of the first coil winding 2 and the second coilwinding 3 in such a manner that the outer leg 52 of the magnetic coremember 5A and the outer leg 56 of the magnetic core member 5B abutagainst each other and furthermore the outer leg 53 of the magnetic coremember 5A and the outer leg 57 of the magnetic core member 5B abutagainst each other. In this case, since the flange section 11 of thecoil bobbin 1 is larger than the first coil winding 2 and furthermorethe side wall section 15 is formed on the outer side of the second coilwinding 3, then the flange section 11 and the side wall section 15function as an insulating member which prevents contact between themagnetic core members 5A, 5B, and the first coil winding 2 and thesecond coil winding 3.

The projecting sections 12A to 12C in the coil bobbin 1 function asinsulating members for preventing abutment between the magnetic coremember 5A and the winding member 21, and the projecting sections 14A and14B and the hook section 16C function as insulating members forpreventing abutment between the magnetic core member 5B and the windingmember 31.

Moreover, outwardly projecting guide sections 19A to 19D are provided onthe flange section 11 of the coil bobbin 1, and these guide sections 19Ato 19D fix the outer legs 56, 57 of the magnetic core member 5B, therebysuppressing the occurrence of positional displacement between themagnetic core member 5B and the coil 1B, in the width direction. Theshape of the guide sections 19A to 19D is not limited to that describedabove, and may be varied appropriately in accordance with the shape ofthe magnetic core members.

(Switching Power Source Apparatus)

Next, a switching power source apparatus in which the coil component 1relating to the present embodiment is desirably used will now bedescribed. FIG. 15 is a circuit diagram of a switching power sourceapparatus 100. Furthermore, FIG. 16 is a perspective diagram of aswitching power source apparatus 100. The switching power sourceapparatus 100 relating to the present embodiment functions as a DC-DCconverter which, for instance, converts a high-voltage DC input voltageVin supplied from a high-voltage battery, or the like, storing a voltageof approximately 100 V to 500 V, into a low-voltage DC output voltageVout, and supplies this voltage Vout to a low-voltage battery, or thelike, storing a voltage of approximately 12 V to 16 V.

As shown in FIG. 16, the switching power source apparatus 100 has a baseplate 101, and secured to this base plate, an input smoothing capacitor(input filter) 130, a switching circuit 120, a main transformer 140, arectifying circuit 150, and a smoothing circuit 160 constituted by achoke coil (coil component) 170 and an output smoothing capacitor 162.

More specifically, the switching power source apparatus 100 comprises aswitching circuit 120 and an input smoothing capacitor 130 providedbetween a primary side high-voltage line 121 and a primary sidelow-voltage line 122, a main transformer 140 having a primary side and asecondary side transformer coil section 141, 142, a rectifying circuit150 which is connected to the secondary side transformer coil section142, and a smoothing circuit 160 which is connected to the rectifyingcircuit 150.

The switching circuit 120 has a full bridge-type circuit composition,which is constituted by switching elements S1 to S4. The switchingcircuit 120 converts a DC input voltage Vin which is applied between theinput terminals T1 and T2, into an input AC voltage, in accordance witha drive signal supplied from a drive circuit (not illustrated), forinstance.

The input smoothing capacitor 130 smoothens a DC input voltage Vin whichis input from the input terminals T1, T2. The main transformer 140transforms the level of the input AC voltage generated by the switchingcircuit 120 and outputs an output AC voltage. The winding ratio of theprimary side and the secondary side transformer coil sections 141, 142is set appropriately with the voltage transformation ratio. Here, thenumber of windings of the primary side transformer coil section 141 isset to be greater than the number of windings of the secondary sidetransformer coil section 142. The secondary side transformer coilsection 142 is a center tap type of coil, which is wired to the outputterminal T3 via a connecting section C and an output line LO.

The rectifying circuit 150 is a single-phase full-wave rectifyingcircuit consisting of rectifying diodes 151A and 151B. The cathodes ofthe rectifying diodes 151A and 151B are connected to the secondary sidetransformer coil section 142, whereas the anodes are connected to aground line LG and wired to the output terminal T4. By this means, therectifying circuit 150 individually rectifies each half wave period ofthe output AC voltage from the main transformer 140 so as to generate aDC voltage.

The smoothing circuit 160 is constituted by a choke coil 170 and anoutput smoothing capacitor 162. The choke coil 170 is inserted into theoutput line LO. The output smoothing capacitor 162 is connected betweenthe choke coil 170 and the ground line LG in the output line LO.Therefore, the smoothing circuit 160 generates a DC output voltage Voutby smoothing the DC voltage which has been rectified by the rectifyingcircuit 150, and supplies this DC output voltage Vout to a low-voltagebattery, or the like, from the output terminals T3, T4.

In the switching power source apparatus 100 which is composed asdescribed above, the DC input voltage Vin supplied from the inputterminals T1, T2 is switched to generate an input AC voltage, which issupplied to the primary side transformer coil section 141 of the maintransformer 140. The generated input AC voltage is transformed andoutput as an output AC voltage from the secondary side transformer coilsection 142. This output AC voltage is rectified by the rectifyingcircuit 150 and smoothed by the smoothing circuit 160, and is thenoutput as a DC output voltage Vout from the output terminals T3, T4.

In the switching power source apparatus 100 described above, the coilwindings become hot when the coil component 1C relating to the presentembodiment is installed and driven, and therefore it is necessary toprovide heat radiating means. Therefore, in the coil component 1Crelating to the present embodiment, the heat radiating section 28provided in the winding member 22 of the first coil winding 2 and theheat radiating section 35 provided in the winding member 31 of thesecond coil winding 3 function as effective heat radiating means.

This composition is described in more concrete terms below withreference to FIG. 17 and FIG. 18. FIG. 17 is an exploded perspectivediagram when the heat radiating member is installed on the coilcomponent, and FIG. 18 is a perspective diagram of the coil component inwhich the heat radiating member has been installed.

More specifically, when the coil component 1C is arranged on the frameof the switching power source apparatus 100, heat radiating sheets 9Aand 9B are provided below the heat radiating section 28 and the heatradiating section 35, as illustrated in FIG. 17 and FIG. 18. A pressingmember 8A having elastic properties for respectively pressing the upperparts of the cover section 17B which covers the heat radiating section28 and the cover section 18A which covers the heat radiating section 35is placed thereon, and is fixed to the frame (heat radiating object) bya screw 8B. The coil component formed by combining these elements is thecoil component 1D shown in FIG. 18. In this case, the center of thepressing member 8A is fixed to the frame by the screw 8B, and due toflexion of the respective ends of this pressing member 8A, the heatradiating section 28 and the heat radiating section 35 are pressedagainst the frame via the heat radiating sheets 9A and 9B. By thismeans, the heat generated by the first coil winding 2 can be radiated tothe frame via the heat radiating section 28, in addition to which theheat generated by the second coil winding 3 can be radiated to the framevia the heat radiating section 35.

In general, in order to radiate heat from coil windings, heat radiationis performed by thermally connecting the coil windings with a frame, orthe like, via an insulating member, such as a heat radiating sheet.Here, a method of respectively fixing the heat radiating sections 28 and35 which form heat radiating terminals by screw fastening to the frameis employed as a method of achieving thermal connection. In this case,an insulating spacer is required in order to achieve insulation betweenthe screw and the heat radiating terminals. On the other hand, in thecoil component 1C relating to the present embodiment, the pressingmember 8A is composed so as to press against the frame by pressing theheat radiating sections 28, 35 forming heat radiating terminals via thecover sections 17B and 18A of the coil bobbin 1. Therefore, a spacer forachieving insulation between the screw and the heat radiating terminalsis not required, and furthermore, a larger surface area can be ensuredfor the heat radiating terminals which are connected thermally to theframe, since no screw hole is required therein. Consequently, the heatradiating properties can be further improved.

As described above, according to the coil bobbin, the coil component andthe switching power source apparatus relating to the present embodiment,the adjacent winding members 21, 22 of the first coil winding 2 areinsulated from each other by the projecting section 13. Furthermore, thefirst coil winding 2 and the second coil winding 3 are insulated fromeach other by the flange section 11. Moreover, the projecting sections12A to 12C and the projecting sections 14A and 14B are respectivelyprovided in positions at either end when the first coil winding 2 andthe second coil winding 3 are viewed in a direction perpendicular to thedirection of the axis line A. Consequently, even with a coil windinghaving three turns, insulation between the windings is achieved by meansof this coil bobbin 1, and furthermore, insulation is also achieved inthe region outside the coil windings as viewed in a directionperpendicular to the axis line direction, thereby making it possible toimprove the insulating properties without increasing the number ofparts.

Moreover, by making the flange section 11 larger than the outer diameterof the coil windings and providing a side wall section 15 which extendsin the direction of axis line A from the outer circumferential edge ofthe flange section 11, then it is possible to achieve insulatingproperties between the coil windings and members such as the magneticcore members, and the like, provided to the outside thereof, as well asachieving stability when installing the coil windings on the coilbobbin.

By providing a hook section 16 which extends in the direction of theaxis line A from the side wall section 15, the hook section 16 pressesin the second coil winding 3, which is provided in the direction ofextension of the side wall section 15, when viewed from the directionperpendicular to the direction of the axis line A, and therefore it ispossible to suppress vibration of the second coil winding 3 in thedirection of the axis line A with respect to the coil bobbin 1.

Furthermore, in the coil bobbin 1 described above, the wall section 17Aand the side wall section 15 function as rotation restricting means forrestricting rotation of the coil winding in one direction. Accordingly,it is possible to prevent the coil windings from coming into contactwith other components, for example, due to rotating about the perimeterof the tubular section 10 of the coil bobbin 1, and hence the insulatingproperties can be raised further.

Moreover, since the hook section 17C and the hook section 18B functionas reversal restricting means for restricting rotation of the coilwindings in the direction opposite to the one direction described above,then rotation of the coil windings in the opposite direction is alsosuppressed and the coil windings can be fixed more appropriately at aprescribed position.

Furthermore, in the coil bobbin 1 described above, cover sections 17Band 18A are provided as spacer sections which abut against the heatradiating sections 28 and 35 that form heat radiating terminals, from adirection following the axis line of the tubular section 10. Here, whenperforming heat radiation from the coil windings, since the coversections 17B and 18A which abut against the heat radiating terminalswhen the coil windings are fixed to the heat radiating object functionas insulating members, then the radiation of heat from the coil windingsis raised without increasing the number of parts.

Furthermore, in the coil component 1D which is provided with the heatradiating means described above, a heat radiating section 28 which is aheat radiating terminal of the first coil winding 2 and a heat radiatingsection 35 which is a heat radiating terminal of the second coil winding3 are pressed in the direction of the axis line A via the cover sections17B and 18A which function as spacer sections. Therefore, these heatradiating terminals are fixed in position and radiation of heat towardsthe frame, which is the heat radiating object, is performed. Here, theheat radiating terminals are fixed to the heat radiating object bypressing of the heat radiating terminals, and therefore it is possibleto increase the contact surface area and further raise the heatradiating properties compared to a case where the heat radiatingterminals are provided with screw holes and are fixed by screws, forexample.

An embodiment of the present invention was described above, but thepresent invention is not limited to the embodiment given here and may bemodified in various ways. For example, the shape of the flange section11 is not limited to that described above and may be modifiedappropriately.

Furthermore, the notch sections 211 to 213, 221 to 223, 311 and 312 weretaken to have a substantially square shape in the embodiment describedabove, but the notch sections are not limited to having this shape andit is possible to provide V-shaped notches or notches with slopingsides. In this case, the shape of the projecting sections 12A to 12C,14A and 14B should be matched to the shape of the notch sections 211 to213, 221 to 223, 311 and 312.

Furthermore, the angles of the notch sections 211 to 213, 221 to 223 inthe first coil winding 2 may all be equal, but as described in theembodiment given above, desirably, the notch sections are provided inpositions which do not have rotational symmetry. By arranging the notchsections in this way, installation becomes easier, because theprojecting sections 12A to 12C and the notch sections 211 to 213 do notall become superimposed with each other again during the fitting of thecoil bobbin 1 onto the first coil winding 2.

Furthermore, in the embodiment described above, the number of turns inthe first coil winding 2 is two turns, and the number of turns in thesecond coil winding 3 is one turn, but the number of turns of therespective windings may be increased. If the number of turns of the coilwindings is increased, then desirably, a member which functions as aspacer for achieving insulation between the windings is also provided.

Furthermore, when viewed in the direction perpendicular to the axis lineA, at least one of the projecting sections 12A to 12C (first projectingsections), 13 (second projecting section), 14A and 14B (third projectingsections) should be present at each position, and the number ofprojecting sections may be varied appropriately.

Furthermore, there are no particular restrictions on the shape of thecover sections 17B and 18A. Moreover, the position of the hook sectionwhich functions as rotation restricting means and reversal restrictingmeans is not limited to that described above and may be modifiedappropriately in accordance with the shape of the flange section 11 andthe side wall section 15, the shape of the coil windings, and the like.

Furthermore, the shape of the pair of magnetic core members 5A and 5B isnot limited to a so-called E-E shape, as indicated in the embodimentdescribed above. For example, it is also possible to use a magnetic coremember having an E-I shape, a U-I shape, a U-U shape, or the like. Inthis case, the winding component relating to the present embodiment canbe used appropriately for the leg section about which the coil windingis wound, of the leg sections of the magnetic core member.

Furthermore, the composition of the switching power source apparatus isnot limited to that shown in FIG. 15 and FIG. 16. In other words, thecoil bobbin 1 relating to the present embodiment is suitable for use inan inverter, for example. Moreover, the coil component 1C (1D) is notlimited to use as a choke coil 70 in the switching power sourceapparatus 100, and is also suitable for use in the main transformer 140.

What is claimed is:
 1. An insulating coil bobbin having a tubularsection about which two conductive coil windings are wound, the coilbobbin further having: a flat-shaped flange section which projectsoutwards from substantially a central portion of the tubular section ina plane which is perpendicular to an axis line of the tubular section; afirst projecting section which projects toward outside from the tubularsection with respect to the axis line at a position separated from theflange section, the first projecting section projecting further towardoutside than a first coil winding, which has two or more turns, of thetwo coil windings, when the first coil winding is wound on a first endside, this first end side being one end side of the tubular section asdivided by the flange section and being the side where the first coilwinding is wound; a second projecting section, which is provided so asto be sandwiched between adjacent windings when the first coil windingis wound on the first end side and which projects toward outside fromthe tubular section with respect to the axis line, in a directiondifferent from the first projecting section when viewed in the axis linedirection; and a third projecting section which projects toward outsidefrom the tubular section with respect to the axis line at a positionseparated from the flange section, the third projecting sectionprojecting further toward outside than a second coil winding, which isdifferent from the first coil winding, of the two coil windings, andwhich has one or more turns, when the second coil winding is wound on asecond end side, this second end side being a different end side fromthe first end side of the tubular section and being a side where thesecond coil winding is wound, wherein the flange section has an outerdiameter larger than an outer diameter of the coil windings andcomprises a side wall section extending in the axis line direction froman outer circumferential edge thereof, and a height of the side wallsection in the axis line direction is greater than a thickness of a coilwinding provided in the direction in which the side wall sectionextends, and the side wall section further has a hook section whichextends in the axis line direction from an end of the side wall sectionthat is different from an end on a side of the flange section.
 2. Thecoil bobbin according to claim 1, further comprising rotationrestricting means for restricting rotation in one direction of the coilwinding, by abutting against the coil winding when the coil winding isinserted into the tubular section and rotated.
 3. The coil bobbinaccording to claim 2, further comprising reversal restricting means forrestricting rotation of the coil winding in a reverse direction at aposition where rotation of the coil winding in the one direction hasbeen restricted by the rotation restricting means.
 4. A coil component,comprising: the coil bobbin according to claim 1; a first coil windingwhich is wound in two or more turns about the axis line; a second coilwinding which is wound in one or more turns about the axis line; aconnecting member which connects one end section of the first coilwinding with one end section of the second coil winding; and a pair ofmagnetic core members which sandwich the coil windings in the axis linedirection.
 5. A switching power source apparatus comprising the coilcomponent according to claim 4.